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Astronomers said on Wednesday that the most thorough study to
date of the star, officially called KIC 8462852, showed that its
dimming episodes are not caused by a large opaque object passing
in front of it. The dimming could be due to some sort of dust,
they added, though the cause remains uncertain.
The researchers relied on observations of Tabby's Star from
March 2016 to December 2017 using Las Cumbres Observatory
telescopes in Maui and the Canary Islands. The star is named
after Louisiana State University astrophysicist Tabetha
Boyajian, who was instrumental in identifying its idiosyncrasies
in 2015.
Beginning in May 2017, the scientists observed four episodes
when the star's light dipped. The data showed less dimming in
the star's red light than in its blue light, and a large opaque
object would dim all colors of light equally when passing in
front of a star, Boyajian said.
"We took measures of the star's brightness in several colors.
Data taken in this way can inform us on what kind of material is
passing in front of the star," Boyajian added.
Numerous hypotheses have been offered about the star's
occasional dimming, including a hypothetical mega-structure
called a Dyson Sphere built to surround a star and harvest its
energy output.
"Sure, it's disappointing that this isn't the anomaly that will
turn out to be that big discovery. But we always knew the
chances were low. It's like finding out that your lottery ticket
isn't a winner: disappointing, but not surprising," said another
of the researchers, Penn State astrophysicist Jason Wright.
Tabby's star, roughly 40 percent more massive than the sun, is
located about 1,280 light-years away from our solar system in
the constellation Cygnus. Its light has been observed dimming as
much as 22 percent.
The new observations were consistent with the effects of dust --
fine grains of material -- on the starlight, Wright said. There
was no hint of gas along with the dust, Wright said.
"We still aren't 100 percent sure where the dust is, but it
seems to be somewhere around the star," Wright added. "We're
still not sure where it's coming from -- maybe colliding
asteroids or comets."
The findings were published in The Astrophysical Journal
Letters.
(Reporting by Will Dunham; Editing by Sandra Maler)
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